In recent years, with popularization of mobile devices and sharp increasing of mobile data flow and wired network data flow, a network capacity pressure of an operator surges. However, frequency spectrum resources are in shortage; and in licensed frequency bands, especially expensive low frequency-band resources, not only a frequency channel available is limited, but also are consumed by rapidly increased user group. In world-wide, 5 GHz license-free frequency bands still have quite a part available frequency spectrum, and operators and equipment manufactures seek to use un-licensed frequency spectrums to enhance network capacities. Accordingly, LAA (License Assisted Access) technology, also known as licensed frequency band assisted license-free frequency spectrum access technology, emerges. The LAA technology uses license-free frequency band to carry data flow of mobile service, so as to enlarge the network capacity.
In existing technologies, whereas the LAA takes a licensed frequency band based on a network architecture of a carrier aggregation as a PCell (Primary Cell) to provide a reliable control signal to guarantee a mobility and meet requirements of QoS (Quality of Service) of the real-time data service, the license-free frequency band serves as a SCell (Secondary Cell) mainly to meet requirements of best effort and support a full-downlink or an uplink and downlink transmission. The LAA applies a cross carrier scheduling and a self-scheduling of a conventional CA (Carrier Aggregation) to realize scheduling. That is to say, a UE (User Equipment) receives DCI (Downlink Control Information) on a carrier appointed by the scheduling according to network scheduling information. The existing technologies inform the UE about carrier information mainly by pre-configuring a scheduling via applying an eNB (Evolved Node B).
However, if the above recited way of scheduling is applied to a un-licensed frequency spectrum, when a base station senses a carrier of the pre-configured scheduling and finds out that the carrier can not be used currently, the scheduling, the sensing and transmitting of information will be implemented again, which further delays the UE for receiving the information. In particularly, for an uplink HARQ (Hybrid Auto Repeat Request), with above described way, a much longer delay will be brought, which will cause low efficiency and bad user experience.